Method for monitoring an operating state of a pumping device

Abstract

A method is for surveillance of an operating state of a pumping device connected to a process chamber in order to determine a failing operating state of the pumping device. The pumping device includes at least one rough-vacuum pump including a motor for driving the rough-vacuum pump and a variable speed drive to control the rotation speed of the motor, to receive a first input parameter corresponding to a set point frequency and a second input parameter corresponding to a motor current, and to deliver to the motor an output parameter corresponding to a control frequency. A failing operating state is determined when in steady-state operation the difference between the first input parameter and the output parameter is equal to or exceeds 10% of the first input parameter for a predetermined time greater than 3 seconds. The method can be implemented in a pumping device and an installation.

1 - 12 . (canceled) 
     
     
         13 . A method for surveillance of an operating state of a pumping device connected to a process chamber in order to determine a failing operating state of the pumping device, the pumping device comprising at least one rough-vacuum pump comprising:
 a motor for driving the rough-vacuum pump, and   a variable speed drive configured to control the rotation speed of the motor, and configured to receive a first input parameter corresponding to a set point frequency and a second input parameter corresponding to a motor current and configured to deliver to the motor an output parameter corresponding to a control frequency,   the method comprising:   determining a failing operating state when, in steady-state operation, a difference between the first input parameter and the output parameter is equal to or exceeds 10% of the first input parameter for a predetermined time greater than 3 seconds.   
     
     
         14 . The method according to  claim 13 , wherein the failing operating state is determined when, in steady-state operation, the difference between the first input parameter and the output parameter is equal to or exceeds 4% of the first input parameter for the predetermined time. 
     
     
         15 . The method according to  claim 13 , wherein the predetermined time is greater than 10 seconds. 
     
     
         16 . The method according to  claim 13 , wherein the predetermined time is less than 30 seconds. 
     
     
         17 . The method according to  claim 13 , wherein, on starting the rough-vacuum pump, the variable speed drive is commanded to increase the control frequency progressively until the set point frequency is reached. 
     
     
         18 . The method according to  claim 13 , wherein, in steady-state operation, the set point frequency is constant at least for a time greater than or equal to the predetermined time. 
     
     
         19 . The method according to  claim 13 , wherein, when the control frequency increases and the motor current exceeds an acceleration current threshold, the variable speed drive blocks the increase in the control frequency. 
     
     
         20 . The method according to  claim 13 , wherein, when the variable speed drive is in steady-state operation and the motor current exceeds an operating current threshold, the variable speed drive reduces the control frequency. 
     
     
         21 . The method according to  claim 13 , wherein, when the difference between the first input parameter and the output parameter is equal to or exceeds 90% of the first input parameter for a predetermined time greater than one minute, an alert or an alarm is triggered. 
     
     
         22 . A pumping device, comprising:
 at least one rough-vacuum pump including:
 a motor for driving the rough-vacuum pump, and 
 a variable speed drive configured to control the rotation speed of the motor, and configured to receive a first input parameter corresponding to a set point frequency and a second input parameter corresponding to a motor current and configured to deliver to the motor an output parameter corresponding to a control frequency; and 
   a surveillance unit configured for surveillance of an operating state of a pumping device in accordance with the method according to  claim 13 .   
     
     
         23 . The pumping device according to  claim 22 , further comprising a Roots Blower mounted in series with and on an upstream side of the rough-vacuum pump. 
     
     
         24 . An installation comprising:
 a process chamber connected by a pipe to an intake of the pumping device according to  claim 22 .